1. Field of the Invention
This invention relates to the protection of organic materials, such as rubber, plastic, lubricating oils, petroleum fuels, waxes, and organic liquids, from oxidation by the use of antioxidants that are N-aromatic substituted acid amide compounds.
In a preferred embodiment, the present invention is directed to lubricants, especially lubricating oils. More particularly, the invention relates to a class of dispersant additives having antioxidant and viscosity index improving credit that are preferably derived from an ethylene-propylene diene modified terpolymer (EPDM) or an ethylene-propylene copolymer and an N-aromatic substituted acid amide compound.
2. Description of Related Art
Organic materials such as rubber, plastic, lubricating oils, petroleum fuels, waxes, and organic liquids are well known to need protection from oxidation.
Currently, many of these organic materials are being exposed to higher operating temperatures and mechanical shear. New stabilizers that can protect organic materials from premature oxidation and degradation under these advanced operating conditions are being sought.
Further, in developing lubricating oils, there have been many attempts to provide additives that provide a lubricating oil with dispersancy of sludge and soot as well as high temperature deposit control. In addition, the formulation of an oil to meet high and low temperature viscosity requirements is critical and, in most cases, a viscosity index improver is employed to achieve this goal. Most multifunctional additives of the prior art provide one or two of these features.
It is well-known that internal combustion engines operate under a wide range of temperatures, including low temperature stop-and-go driving service, as well as high-temperature conditions produced by continuous high speed driving. Stop-and-go driving, particularly under cold, damp weather conditions, leads to the formation of sludge in the crankcase and in the oil passages of a gasoline or a diesel engine. This sludge seriously limits the ability of the crankcase engine oil to lubricate the engine effectively. In addition, the sludge, with its entrapped water, tends to contribute to rust formation in the engine. These problems can be aggravated by engine manufacturers' lubrication service recommendations, which typically specify extended oil drain intervals.
Additives that protect engines against sludge formation generally contain nitrogen. These additives are also known as dispersants and/or detergents in the formulation of crankcase lubricating oil compositions. The preparation of many of the known dispersant/detergent compounds is based on the reaction of an alkenylsuccinic acid or anhydride with an amine or polyamine to produce an alkenyl succinimide or an alkenylsuccinamic acid or anhydride as an intermediate. This is advantageous since these products, if not completely reacted with amine or polyamine, can cause rust in an engine.
It is common practice to chlorinate the alkenyl group either before or after reaction with the acid anhydride, but prior to reaction with the amine or polyamine, in order to produce a reaction product in which a portion of the amine or polyamine is attached directly to the alkenyl moiety. The thrust of many of these processes is to produce a product having a relatively high level of nitrogen in order to provide improved dispersancy. However, chlorine is an environmentally undesirable by-product of such processes, and it would therefore be advantageous to achieve relatively high levels of nitrogen without the use of chlorine.
Ethylene-propylene copolymers and ethylene-alpha olefin non-conjugated diene terpolymers that have been grafted and derivatized to provide valuable properties in lubricating oil compositions are well known.
Aralkyl-substituted diarylamines, such as 4,4′-bis(α,α-dimethylbenzyl)diphenylamine (NAUGARD 445, Uniroyal Chemical), and their use as antioxidants for a variety of polymeric materials are known from U.S. Pat. Nos. 3,452,056 and 3,505,225.
Additionally, aromatic amines have also been used as stabilizers of organic materials, especially for use in plastic, rubber, and oils. For example, U.S. Pat. No. 3,505,225 describes aromatic amine antioxidants based on α-methylstyryl-substituted diphenylamines.
U.S. Pat. No. 3,522,180 discloses a method for the preparation of an ethylene-propylene copolymer substrate effective as a viscosity index improver for lubricating oils.
U.S. Pat. No. 4,026,809 discloses graft copolymers of a methacrylate ester and an ethylene-propylene-alkylidene norbornene terpolymer as a viscosity index improver for lubricating oils.
U.S. Pat. No. 4,089,794 discloses ethylene copolymers derived from ethylene and one or more C3 to C28 alpha olefins solution-grafted with an ethylenically-unsaturated carboxylic acid material followed by a reaction with a polyfunctional material, such as a polyamine, a polyol, or a hydroxylamine that is reactive with the carboxyl groups of the acid.
U.S. Pat. No. 4,096,319 discloses polymers containing anti-oxidant functionality that are said to be useful as viscosity index (VI) improvers for high temperature service. The anti-oxidant moiety is said to prevent extensive oxidative decomposition of the polymer making the polymers particularly useful with lubricating oils used in diesel engines. A method of preparing the antioxidant-containing VI improver polymer by esterifying a carboxylic acid-containing polymer with an N-methyl hydroxyethyl amide-containing antioxidant is also disclosed.
U.S. Pat. Nos. 4,137,185 and 4,144,181 disclose an oil-soluble, derivatized ethylene copolymer derived from about 2 to 98 wt. percent ethylene, and one or more C3 to C28 alpha-olefins, e.g., propylene. These compounds are preferably solution-grafted under an inert atmosphere and at elevated temperatures in the presence of a high-temperature, decomposable free-radical initiator with an ethylenically-unsaturated dicarboxylic acid material. Thereafter, the graft copolymer is reacted with a polyamine having at least two primary amine groups, e.g., an alkylene polyamine such as diethylene triamine, to form carboxyl-grafted polymeric imide, usually maleimide, derivatives. The derivatives are reacted with an anhydride of a C1 to C30 hydrocarbyl substituted acid, preferably acetic anhydride, to yield an oil-soluble, stable amide derivative of the polyamine that exhibits minimal viscosity change over an extended period of time. Useful number average molecular weights (Mn) of the copolymers range from about 700 to 500,000. If the molecular weight is in the range of 10,000 to 500,000, then these copolymers are also useful as multifunctional viscosity index improvers.
U.S. Pat. No. 4,146,489 discloses graft copolymers wherein the backbone polymer is a rubbery, oil-soluble ethylene-propylene copolymer or ethylene-propylene diene modified terpolymer and the graft monomer is a C-vinylpyridine or N-vinylpyrrolidone that imparts dispersant properties to hydrocarbon fuels and combined viscosity index improvement and dispersant properties to lubricating oils for internal combustion engines. The graft copolymers are prepared by intimate admixture of the backbone polymer, monomer to be grafted, and a free radical initiator at a temperature below initiation temperature, followed by a temperature increase to or above the initiation temperature, thus providing a product containing little or no by-product.
U.S. Pat. No. 4,234,435 discloses carboxylic acid acylating agents derived from polyalkenes and a carboxylic reactant having a molecular weight from about 1,300 to 5,000 and having at least 1.3 carboxylic groups per equivalent of polyalkene.
U.S. Pat. No. 4,320,019 discloses a multipurpose lubricating additive prepared by the reaction of an interpolymer of ethylene and a C3 to C8 alpha-monoolefin with an olefinic carboxylic acid acylating agent to form an acylating reaction intermediate that is then reacted with an amine.
U.S. Pat. No. 4,340,689 discloses a process for grafting a functional organic group onto an ethylene copolymer or an ethylene-propylene-diene terpolymer.
U.S. Pat. No. 4,357,250 discloses a reaction product of a copolymer and an olefin carboxylic acid via the “ene” reaction followed by a reaction with monoamine-polyamine mixture.
U.S. Pat. No. 4,382,007 discloses a dispersant-viscosity index improver prepared by reacting a polyamine-derived dispersant with an oxidized ethylene-propylene polymer or an ethylene-propylene-diene terpolymer.
U.S. Pat. No. 4,668,834 discloses low molecular weight copolymers comprised of ethylene, an alphaolefin and, optionally, a nonconjugated polyene, which copolymers have a viscosity index of at least about 75 and vinylidene-type unsaturation. The copolymers are said to possess unexpected advantages as intermediates in epoxy-grafted electrical encapsulation compositions.
U.S. Pat. Nos. 4,797,511 and 4,837,259 describe synergistic blends of hindered phenols and amine antioxidants as stabilizers for polypropylene and polyethylene.
U.S. Pat. No. 4,863,623 discloses multifunctional grafted and derivatized copolymers that provide viscosity index improvement, dispersancy, and antioxidant properties in a multigrade lubricating oil composition. The additive composition comprises a graft and amine-derivatized copolymer prepared from ethylene and at least one C3 to C10 alpha-monoolefin and, optionally, a polyene selected from non-conjugated dienes and trienes comprising from about 15 to 80 mole percent of ethylene, from about 20 to 85 mole percent of the C3 to C10 alpha-monoolefin, and from about 0 to 15 mole percent of the polyene having an average molecular weight ranging from about 5,000 to 500,000, which has been reacted with at least one olefinic carboxylic acid acylating agent to one or more acylating reaction intermediates characterized by having a carboxylic acid acylating function within their structure and reacting the reaction intermediate with an amino-aromatic polyamine compound. The amino-aromatic polyamine compound is a member selected from the group consisting of an N-arylphenylenediamine, an aminothiazole, an amino carbazole, an aminoindole, an aminopyrrole, an amino indazolinone, an aminomercaptotriazole, and an aminoperimidine to form the graft and amine-derivatized copolymer. A lubricating oil composition containing the additive is also disclosed.
U.S. Pat. No. 4,904,403 discloses compounds derived from 2,5-dimercapto-1,3,4-thiadiazole and one or two moles of polyolefin having 5 to 400 carbon atoms. The 5-position of the 2-mercapto-1,3,4-thiadiazole can be substituted by an alkylthio, a 2-hydroxyalkylthio, an amino, or a hydroxy group. The compounds are said to be effective dispersants, antiwear agents, and antioxidants when incorporated into lubricating compositions.
U.S. Pat. No. 4,990,274 discloses an oil additive composition comprising    (1) a mixture of a graft and derivatized polymer and a mineral oil of lubricating viscosity said mixture comprising from about 5 to 35 weight percent of said polymer and the balance said mineral oil and having a bulk viscosity measured as the Kinematic Viscosity at 100° C. above about 2000 Centistokes, and    (2) a minor amount of a co-solvent of defined structure effective for substantially reducing the bulk viscosity of said mixture.
U.S. Pat. No. 5,021,177 discloses dispersant viscosity index improvers for lubricating oils containing and EPR or EPT polymer onto which has been graft polymerized with isocyanatoethyl methacrylate and thereafter reacted with N-phenyl-p-phenylene diamine.
U.S. Pat. No. 5,047,530 discloses tris(N-alkyl-p-phenylenediamino)-1,3,5-triazine compounds useful as antiozonants for unsaturated high polymers. The compounds can be prepared by reacting N-alkylphenylenediamine with a cyanuric halide.
U.S. Pat. No. 5,075,383 discloses an additive composition comprising a graft and amine-derivatized copolymer prepared from ethylene and at least one C3 to C10 alpha-monoolefin and, optionally, a polyene selected from non-conjugated dienes and trienes comprising from about 15 to 80 mole percent of ethylene, from about 20 to 85 mole percent of the C3 to C10 alpha-monoolefin and from about 0 to 15 mole percent of the polyene. The copolymer has an average molecular weight ranging from about 5,500 to 50,000 and has grafted thereon at least 1.8 molecules of a carboxylic acid acylating function per molecule of the copolymer. The grafted copolymer is reacted with an amino-aromatic polyamine compound from the group consisting of an N-arylphenylenediamine, an aminocarbazole, and an aminoperimidine to form the graft and amine-derivatized copolymer. A lubricating oil composition containing the additive is also disclosed.
U.S. Pat. No. 5,094,766 discloses dispersant and antioxidant viscosity index improvers for lubricating oils containing and EPR or EPT polymer onto which has been graft polymerized with vinyl azlactone and thereafter reacted with N-phenyl-p-phenylene diamine.
U.S. Pat. No. 5,120,844 discloses tris-substituted 1,3,5-triazine compounds having at least one (N-alkyl-p-phenylenediamino) group on the triazine ring. The preferred compositions are tri-substituted with the alkyl p-phenylenediamino group. The preferred compounds can be prepared by reacting N-alkylphenylenediamine with a cyanuric halide.
U.S. Pat. No. 5,162,086 discloses an additive composition comprising a graft and amine-derivatized copolymer prepared from ethylene and at least one C3 to C10 alpha-monoolefin and, optionally, a polyene selected from non-conjugated dienes and trienes comprising from about 15 to 80 mole percent of ethylene, from about 20 to 85 mole percent of the C3 to C10 alpha-monoolefin and from about 0 to 15 mole percent of the polyene. The copolymer has a number average molecular weight ranging from about 5,500 to 50,000 and has grafted thereon at least 1.8 molecules of a carboxylic acid acylating function per molecule of the copolymer. The grafted copolymer is reacted with an amine substituted phenothiazine to form the graft and amine-derivatized copolymer. A lubricating oil composition containing the additive is also disclosed.
U.S. Pat. No. 5,188,745 discloses an additive composition comprising a graft and amine-derivatized copolymer prepared from ethylene and at least one C3 to C10 alpha-monoolefin and, optionally, a polyene selected from non-conjugated dienes and trienes comprising from about 15 to 80 mole percent of ethylene, from about 20 to 85 mole percent of the C3 to C10 alpha-monoolefin, and from about 0 to 15 mole percent of the polyene. The copolymer has an average molecular weight ranging from about 5,500 to 500,000 and has been reacted with at least one olefinic carboxylic acid acylating agent to form one or more acylating reaction intermediates characterized by having a carboxylic acid acylating function within their structure. This reaction intermediate is then reacted with an N-(2-aminoalkyl)imidazolidone to form the graft derivatized copolymer. A lubricating oil composition containing the additive is also disclosed.
U.S. Pat. No. 5,200,102 discloses an additive composition comprising a graft and derivatized copolymer prepared from ethylene and at least one C3 to C10 alpha-monoolefin and, optionally, a polyene selected from non-conjugated dienes and trienes comprising from about 15 to 80 mole percent of ethylene, from about 20 to 85 mole percent of the C3 to C10 alpha-monoolefin and from about 0 to 15 mole percent of the polyene having an average molecular weight ranging from about 5,000 to 500,000, which has been reacted with at least one olefinic carboxylic acid acylating agent to form one or more acylating reaction intermediates characterized by having a carboxylic acid acylating function within their structure. The reaction intermediate is reacted with an amino alkylthio thiadiazole to form the graft derivatized copolymer. A lubricating oil composition containing the graft derivatized copolymer is also disclosed.
U.S. Pat. No. 5,474,694 discloses an additive composition comprising a graft and amine-derivatized copolymer prepared from ethylene and at least one C3 to C10 alpha-monoolefin and, optionally, a polyene selected from non-conjugated dienes and trienes comprising from about 15 to 80 mole percent of ethylene, from about 20 to 85 mole percent of the C3 to C10 alpha-monoolefin, and from about 0 to 15 mole percent of the polyene. The copolymer has a number average molecular weight ranging from about 5,500 to 50,000 and has grafted thereon at least 1.8 molecules of a carboxylic acid acylating function per molecule of the copolymer. The grafted copolymer is reacted with an amino alcohol compound selected from the group consisting of a 2-anilinoalcohol, a (2-hydroxyalkyl)pyridine, a 4-(2-hydroxyalkyl)morpholine, a 1-(2-hydroxyalkyl)piperazine, and a 1-(2-hydroxyalkyl)2-pyrrolidine.
U.S. Pat. No. 5,556,923 discloses a continuous process for producing a adducted derivatized EPM or EPDM oil solution, in which a grafted ethylene polymer is adducted with an antioxidant diamine for formation of an adduct during holding.
U.S. Pat. No. 5,698,500 discloses a graft copolymer prepared by the interpolymerization of a mixture of monomers comprising ethylene, a C3 to C12 alpha monoolefin, and a polyene being a member selected from the group consisting of non-conjugated dienes and trienes. Grafted to the copolymer is a 2-mercapto-1,3,4-thiadiazole moiety. Lubricating oil additives and lubricating oils comprising the graft copolymer are also disclosed.
U.S. Pat. No. 5,747,433 discloses a composition of about 2 to about 20 percent of a hydrogenated diene/vinyl aromatic block copolymer and a non-ionic surface active agent, soluble in said oil, comprising at least one ester or ether group, in a medium of oil of lubricating viscosity that is said to exhibit reduced viscosity compared with comparable compositions without the surface active agent.
U.S. Pat. No. 5,834,544 discloses compounds containing dual substitutions of an aromatic amine and hindered phenol functionality that are useful as stabilizers for organic materials.
U.S. Pat. No. 6,107,257 discloses an additive comprising a highly grafted, multi-functional olefin copolymer comprising a graft and amine-derivatized copolymer prepared from ethylene and at least one C3 to C23 alpha-monoolefin and, optionally, a polyene, wherein the copolymer of ethylene and at least one C3 to C23 alpha-monoolefin has grafted thereon from 0.3 to 0.75 carboxylic groups per 1000 number average molecular weight units of olefin copolymer and wherein the olefin copolymer has a number average molecular weight of between 20,000 and 150,000, and lubricating oil concentrates and compositions containing the same.
U.S. Pat. No. 6,107,258 discloses a multi-functional fuel and lubricant additive that is said to provide dispersancy properties as well as viscosity index improved credit, improved fuel economy and low temperature viscometric properties. Concentrates, fuel and lubricating oil compositions containing said additive are also disclosed.
U.S. Pat. No. 6,117,825 discloses a lubricating oil composition comprising: (a) a major amount of an oil of lubricating viscosity; and (b) a minor dispersant amount of a synergistic combination of an antioxidant-dispersant additive and a dispersant additive, said combination comprising: (i) a polyisobutylene succinimide; and (ii) an ethylene-propylene succinimide.
EP 0 922 752 A2 discloses an olefin copolymer which comprises the reaction product of an acylated olefin copolymer and a polyamine, wherein the acylated olefin copolymer comprises an olefin copolymer having grafted thereon from 0.3 to 0.75 carboxylic groups per 1000 number average molecular weight units of olefin copolymer and wherein the olefin copolymer has a number average molecular weight of from 20,000 to 150,000. The copolymer is used as an additive in lubricating oil compositions where it acts as a viscosity modifier.
The disclosures of the foregoing are incorporated herein by reference in their entirety.